Multi-magnetic-circuit combined type induction heating device of direct rolling plate blank

Abstract

The invention discloses a multi-magnetic-circuit combined type induction heating device for a direct rolling plate blank. The multi-magnetic-circuit combined type induction heating device comprises a combined type inductor and a motion executing mechanism. The composite inductor comprises an induction heating loop and an E-shaped magnet yoke; the induction heating loop comprises one or more groups of induction coils, a variable-frequency power supply and a cable; the adjacent induction coils are connected in series; the E-shaped magnet yoke comprises an upper magnet yoke and a lower magnet yoke, and a plurality of magnetic teeth facing the straight rolling plate blank are arranged on the sides, close to the straight rolling plate blank, of the upper magnet yoke and the lower magnet yoke. The motion executing mechanism comprises a magnet yoke adjusting mechanism and a coil adjusting mechanism; the magnet yoke adjusting mechanism is used for adjusting the distance between the upper magnet yoke and the lower magnet yoke of the E-shaped magnet yoke and the upper surface and the lower surface of the straight rolling plate blank. And the coil adjusting mechanism is used for adjusting the positions of the one or more groups of induction coils. The distance between the composite inductor and the direct-rolled plate blank is adjusted on line, so that the heating loss of an induced magnetic field is reduced, the induction heating efficiency is improved, the heating quality is high, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of induction heating of direct-rolled slabs, and in particular to a multi-magnetic-circuit composite induction heating device for direct-rolled slabs. Background Art

[0002] Continuous casting and rolling is one of the major advances in the contemporary steel industry. It closely integrates continuous casting and rolling in the traditional steel process, implements direct rolling of continuous casting slabs, eliminates the reheating process of gas heating furnaces, has a compact process, and significantly reduces energy consumption and carbon emissions. CSP, ISP, CONROLL, QSP, FTSR, ASP, ESP and other forms have been developed internationally, and nearly 100 continuous casting and rolling production lines have been built. However, if the hot delivery direct rolling technology is transformed for the existing production line, the fixed-length billet generally needs to be transported by rollers hundreds of meters or even thousands of meters long before it can reach the hot rolling from the continuous casting plant. Due to environmental cooling, roller contact cooling, abnormal retention and other reasons, the surface temperature of the slab often drops to 900-1100℃ or even lower before reaching the rolling unit, making it difficult to meet the rolling temperature requirements of 1200-1300℃. Therefore, to achieve direct rolling, a series of induction heating furnaces must be set up in front of the rolling unit to quickly heat the slab according to the actual temperature of the slab, increase the temperature of the slab, and ensure the stability and smoothness of the rolling process. There are two methods for induction heating of large slabs: static heating, that is, the slab is horizontally erected by the flip lifting mechanism and lifted into the induction coil by the lifting mechanism for static heating. After the heating is completed, it is lowered, flipped and sent to the rolling line for rolling. In this way, the induction coil must surround the entire slab of one or twenty meters long. The induction coil, including the motion actuator, is quite large, and the equipment manufacturing, use and maintenance are very complicated and difficult; the other is dynamic heating, that is, a series of tunnel-type electromagnetic coils are arranged at intervals on the conveyor roller to make the slab inductively heated step by step during its passage. This method is widely used, and most of them use the so-called longitudinal magnetic coil with a single magnetic circuit and a magnetic field direction parallel to the length of the slab. There are many induction coil furnaces (generally, 5 to 20), and when the thickness of the slab changes greatly, it is often necessary to replace coils of different specifications, and the number of spare parts on site increases exponentially.

[0003] In the prior art, Chinese patent application number CN201220092381.7 discloses an online induction heating device for continuous casting and rolling, which includes a conveying device, wherein the conveying device is composed of a plurality of conveying units driven by a variable speed motor or a motor reducer, and the plurality of conveying units are arranged linearly and spaced to form a conveying platform, and an induction heating coil is arranged between the conveying units. The advantages of this technology are: first, the purpose of online automatic heating of the workpiece is achieved, so that the heat of the continuous casting billet itself will not be lost, and the continuous casting billet can be fully and permanently heated for the production and processing of the next link; second, the structure is simple, the operation is convenient, time-saving and labor-saving, the precision is high, the generation of oxide scale on the surface of the continuous casting billet is reduced, the quality of the processed workpiece is ensured, the energy consumption is reduced, the cost is reduced, and the processing profit is maximized; third, it is not only environmentally friendly, but also improves production efficiency. This technology involves a tunnel-type longitudinal magnetic coil, but the structure of the induction coil is not disclosed, and the opening degree of the longitudinal magnetic coil cannot be adjusted, which is difficult to adapt to the changes in the specifications of the slab. In addition, there are many spare parts for the coil on site, which are troublesome to repair and replace.

[0004] Chinese patent application number CN201710011781.8 discloses an induction heating device for continuous casting and rolling of plates and strips, including a plurality of induction heaters arranged side by side with spaced conveying rollers, each of which includes two pairs of planar inductors arranged side by side along the width direction of the plates and strips; each pair of planar inductors consists of a lower plane inductor and an upper plane inductor; the lower plane inductor and the upper plane inductor are arranged correspondingly; the plates and strips can pass between the upper plane inductor and the lower plane inductor through the conveying rollers; the planar inductor includes a planar iron core, and a plurality of teeth are arranged at intervals along the moving direction of the plate on the planar iron core, and tooth slots are formed between two adjacent teeth, and the coil is wound on the teeth of the iron core. This technology involves a planar transverse magnetic coil, which improves the passing performance of different plates and strips, but its electromagnetic field is relatively dispersed and the electromagnetic heating efficiency is relatively low.

[0005] Chinese patent application number CN201310357086.9 discloses a slab loading and unloading device and control method for an electromagnetic induction furnace for oriented silicon steel, the device includes a slab transverse movement device, a transverse movement hydraulic cylinder, a slab turning device, a turning hydraulic cylinder, a slab lifting device, a lifting hydraulic cylinder, a slab guide device, a guide hydraulic cylinder, an upper working full pin, an upper working safety pin cylinder, a slab upper clamping device, a slab upper clamping device cylinder, a furnace bed and a furnace table; the technology solves the problem of taking a slab weighing about 20 tons at 1100℃ from the roller and transporting it to the bottom of the furnace table of the electromagnetic induction furnace and turning it 90 degrees, then vertically supporting the slab upward into the induction heating coil for heating, heating the slab to 1400℃, then dropping the slab from the furnace, turning it flat and transporting it back to the conveying roller table. Although the vertical and static induction heating involved in the technology can meet the high-speed rolling rhythm requirements to a certain extent by increasing the number of induction coil furnace groups, the induction coil furnace including the turning mechanism is very large, and the induction heating efficiency is not high.

[0006] Chinese patent application number CN201320832878.2 discloses a hot delivery and heating device for continuous casting billets, including an elevator, a first main roller, a UV reversing cooling bed, a second main roller and a rolling mill, and also includes a low-temperature heating furnace, a feeding roller, a furnace discharge roller, an induction heater and a waste rejection device. The elevator and UV reversing cooling bed are located on both sides of one end of the first main roller, the low-temperature heating furnace is located on one side of the other end of the first main roller, and the low-temperature heating furnace is connected to the first main roller through the furnace discharge roller; the induction heater is located between the first main roller and the second main roller, and the other end of the second main roller is a rolling mill; the feeding roller goes deep into the low-temperature heating furnace; the waste rejection device is located on one side of the second main roller. Although the buffering effect of the low-temperature heating furnace involved in this technology can reduce power consumption, it does not completely eliminate gas heating, and the overall carbon reduction and emission reduction effect is limited.

[0007] To sum up, the existing slab induction heating technology has problems to varying degrees in terms of heating efficiency, adjustability and equipment cost. Generally speaking, although longitudinal magnetic heating has higher efficiency, it has poor adaptability, and transverse magnetic heating has better adjustable performance but lower efficiency. Therefore, studying a direct-rolled slab heating technology with strong adaptability and high heating efficiency is still an important issue that needs to be urgently solved in the current direct-rolled slab preparation process. Summary of the invention

[0008] In view of the problems of poor adaptability of longitudinal magnetic heating and low efficiency of transverse magnetic heating in the existing slab induction heating technology, the purpose of the present invention is to provide a multi-magnetic circuit composite induction heating device for direct-rolled slabs. By online adjusting the distance between the composite inductor and the direct-rolled slab, the loss of induction magnetic field heating is reduced, the induction heating efficiency is improved, the number of spare parts is reduced, the production cost of strip rolling is reduced, and the goals of green, energy-saving, emission reduction and carbon reduction are better achieved.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] The present invention provides a multi-magnetic circuit composite induction heating device for direct-rolled slabs, comprising a composite inductor and a motion actuator;

[0011] The composite inductor comprises an induction heating circuit and an E-shaped magnetic yoke; the induction heating circuit comprises one or more induction coils arranged side by side in the moving direction of the direct-rolled slab, a variable frequency power supply connected to the induction coils, and a cable connecting the induction coils and the variable frequency power supply; adjacent induction coils are connected in series; the E-shaped magnetic yoke comprises an upper magnetic yoke and a lower magnetic yoke respectively sleeved on the upper and lower sides of the horizontal section of the induction coil, and a plurality of magnetic teeth facing the direct-rolled slab are arranged on the side of the upper magnetic yoke and the lower magnetic yoke close to the direct-rolled slab;

[0012] The motion actuator includes a yoke adjustment mechanism and a coil adjustment mechanism; the yoke adjustment mechanism is used to adjust the distance between the upper yoke and the lower yoke of the E-type yoke and the upper and lower surfaces of the direct-rolled slab; the coil adjustment mechanism is used to adjust the position of one or more groups of induction coils.

[0013] Preferably, the induction coils are wound along the width direction of the direct-rolled slab; and each group of induction coils is disposed between different magnetic teeth of the E-shaped magnetic yoke.

[0014] Preferably, the induction coil is wound with a copper tube, the outer surface of the copper tube is covered with an electrical insulating coating, and the inside of the copper tube is cooled by circulating water.

[0015] Preferably, the inner surface of the induction coil is provided with a refractory insulation layer.

[0016] Preferably, the winding directions of adjacent induction coils are opposite, and the electrode interfaces of adjacent induction coils are connected in sequence; and / or

[0017] The winding directions of adjacent induction coils are the same, and the electrode interfaces of adjacent induction coils are connected in sequence.

[0018] Preferably, the upper magnetic yoke and the lower magnetic yoke are both made of laminated silicon steel sheets, and a refractory insulation layer is provided on the surface of the upper magnetic yoke and the lower magnetic yoke on a side close to the direct-rolled slab.

[0019] Preferably, the number n of the induction coils is 1 to 8, and the number of magnetic teeth of the E-type magnetic yoke is n+1.

[0020] Preferably, the yoke adjustment mechanism comprises a first hydraulic cylinder connected to the upper yoke and a second hydraulic cylinder connected to the lower yoke;

[0021] The coil adjustment mechanism includes a third hydraulic cylinder connected to the one or more groups of induction coils.

[0022] Preferably, the cable is a flexible water-cooled copper cable.

[0023] Preferably, it also includes a control center connected to the motion actuator and the variable frequency power supply; the control center includes a slab detection system, a position controller and a power controller;

[0024] The slab detection system is used to obtain the steel type information, running speed, thickness and surface temperature of the direct-rolled slab;

[0025] The position controller is connected to the slab detection system and the motion actuator respectively, and the position controller adjusts the position of the induction coil and the E-type magnetic yoke of the composite inductor through the motion actuator according to the thickness of the direct-rolled slab;

[0026] The power supply controller is connected to the slab detection system and the variable frequency power supply respectively, and the power supply controller adjusts the output power and current frequency of the variable frequency power supply according to the data detected by the slab detection system.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. Compared with traditional longitudinal magnetic induction heating, the present invention does not require frequent replacement of coils, and the coil position and opening can be adjusted online, which can meet the requirements of induction heating of multi-thickness slabs. The device is flexible, efficient and low-cost;

[0029] 2. Compared with the traditional transverse magnetic induction heating, the induction coil of the present invention is arranged in sections around the slab, and the whole belongs to the longitudinal magnetic heating range. Combined with the regulating function of the E-type magnetic yoke, etc., it can effectively improve the induction heating efficiency;

[0030] 3. Compared with traditional gas heating, the present invention uses electric heating, which has a fast heating speed and is free from the problems of surface oxidation or surface decarbonization that often exist in gas heating. It is green, energy-saving, environmentally friendly and low-carbon;

[0031] 4. The multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention is compact, occupies a small area, has a flexible, ingenious, efficient design, and is easy to use. It can solve the problems of the need to replace the induction furnace when the slab specifications change due to the longitudinal magnetic coil induction heating, the inconvenient adjustment of the induction coil, poor adaptability, and too many spare parts on site;

[0032] 5. The multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention expands the scope of slab induction heating, especially longitudinal magnetic induction heating, to adapt to different slab specifications, improves the quality of slab induction heating, especially the efficiency of slab induction heating, reduces the induction heating cost during slab rolling, especially direct rolling, and is suitable for promotion and application in various continuous casting, continuous rolling or direct rolling production, and has a very broad prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0034] Figure 1 It is a structural schematic diagram of a multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention;

[0035] Figure 2 It is a schematic diagram of the longitudinal magnetic circuit distribution of induction heating of the multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention;

[0036] Figure 3 The diagram is a diagram of the adjustment process of the upper magnetic yoke and the lower magnetic yoke when the multi-magnetic circuit composite induction heating device of the direct-rolled slab of the present invention heats the direct-rolled slabs of different thicknesses; (a) is a diagram of the position relationship between the upper magnetic yoke, the lower magnetic yoke and the direct-rolled slab when the thickness is d1; (b) is a diagram of the position relationship between the upper magnetic yoke, the lower magnetic yoke and the direct-rolled slab when the thickness is d2;

[0037] Figure 4 It is a schematic diagram of the connection between the variable frequency power supply and the induction coil of the multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention;

[0038] Figure 5 It is a schematic diagram of the connection between the motion actuator and the composite inductor of the multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention;

[0039] In the figure, 1. motion actuator, 11. first hydraulic cylinder, 12. second hydraulic cylinder, 13. third hydraulic cylinder, 2. E-type magnetic yoke, 21. upper magnetic yoke, 211. first magnetic tooth, 212. second magnetic tooth, 213. third magnetic tooth, 214. fourth magnetic tooth, 22. lower magnetic yoke, 3. refractory insulation layer of magnetic yoke, 31. refractory insulation layer of upper magnetic yoke, 32. refractory insulation layer of lower magnetic yoke, 4. direct rolling slab, 5. induction coil, 51. first induction coil, 52. The second induction coil, 53, the third induction coil, 511, the starting end of the first induction coil, 512, the terminal end of the first induction coil, 521, the starting end of the second induction coil, 522, the terminal end of the second induction coil, 531, the starting end of the third induction coil, 532, the terminal end of the third induction coil, 6, conveying roller, 7, coil refractory material insulation layer, 8, cable, 9, variable frequency power supply, 100, temperature detection module, 200, distance detection module, 300, control center, 400, rolling mill. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form.

[0041] Combination Figure 1 , Figure 2 As shown, a multi-magnetic circuit composite induction heating device for a straight-rolled slab provided by the present invention comprises a composite inductor and a motion actuator 1. The composite inductor comprises an induction heating circuit and an E-type yoke 2; the induction heating circuit comprises one or more induction coils 5 arranged side by side in the moving direction of the straight-rolled slab 4, a variable frequency power supply 9 connected to the start and end of one or more induction coils 5, and a cable 8 connecting the induction coils 5 and the variable frequency power supply 9; adjacent induction coils 5 are connected in series through the cable 8; the E-type yoke 2 comprises an upper yoke 21 and a lower yoke 22 respectively sleeved on the upper and lower sides of the horizontal section of the induction coil 5, and a plurality of magnetic teeth facing the surface of the straight-rolled slab 4 are arranged on the side of the upper yoke 21 and the lower yoke 22 close to the straight-rolled slab 4. The motion actuator 1 comprises a yoke adjustment mechanism and a coil adjustment mechanism; the yoke adjustment mechanism is used to adjust the distance between the upper yoke 21 and the lower yoke 22 of the E-type yoke 2 and the upper and lower surfaces of the straight-rolled slab 4; the coil adjustment mechanism is used to adjust the position of one or more induction coils 5.

[0042] Combination Figure 1 As shown, the induction coil 5 is wound along the width direction of the direct-rolled slab 4; the inside of the copper tube is cooled by circulating water, and the alternating current is passed through the copper tube wall through the cable 8; the outer surface of the copper tube is coated with an electrical insulating coating, and the inner surface of the induction coil 5 is provided with a coil refractory material insulation layer 7 to prevent the high-temperature steel billet from directly baking the induction coil 5 and affecting the insulation performance and service life of the copper tube;

[0043] In a specific implementation, the induction coil 5 can be spirally wound using a copper tube, such as a pure copper flat tube with high electrical conductivity and high thermal conductivity, and a copper alloy flat tube with higher performance; the cable 8 can be a flexible water-cooled copper cable, such as a flexible water-cooled copper (alloy) cable with high thermal conductivity (high electrical conductivity).

[0044] Combination Figure 1 As shown, one or more groups of induction coils 5 have a rectangular structure as a whole, and the number n of multiple independent groups of induction coils 5 connected by cables 8 is 1 to 8, namely the first induction coil, the second induction coil, ..., the nth induction coil, and each group of induction coils is respectively arranged between different magnetic teeth of the E-type magnetic yoke 2.

[0045] Combination Figure 2 As shown, the winding directions of adjacent induction coils 5 are opposite, and the electrode interfaces of adjacent induction coils 5 are connected in sequence, that is, when the adjacent induction coils 5 are wound clockwise or counterclockwise, or when they are wound counterclockwise or clockwise, the corresponding electrode interfaces are connected through the cable 8 in the terminal-starting end or starting end-terminal direction. For example, when the first induction coil 51 is wound clockwise, the second induction coil 52 is wound counterclockwise, and the third induction coil 53 is wound clockwise, the electrode interface at the terminal 512 of the first induction coil 51 is connected to the electrode interface at the starting end 521 of the second induction coil 52, and the electrode interface at the terminal 522 of the second induction coil 52 is connected to the electrode interface at the starting end 531 of the third induction coil 53. The connections of the remaining induction coils are similar. Alternatively, the winding directions of adjacent induction coils 5 are the same, and the electrode interfaces of adjacent induction coils 5 are connected in sequence, that is, when the adjacent induction coils 5 are wound clockwise, clockwise, or counterclockwise, counterclockwise, the corresponding electrode interfaces are connected through the cable 8 in a terminal-terminal, start-start manner. For example, when the first induction coil 51, the second induction coil 52, and the third induction coil 53 are all wound clockwise, the electrode interface at the terminal 512 of the first induction coil 51 is connected to the electrode interface at the terminal 522 of the second induction coil 52, the electrode interface at the start 521 of the second induction coil 52 is connected to the electrode interface at the start 531 of the third induction coil 53, and the connections of the remaining induction coils are similar.

[0046] Combination Figure 2As shown, the E-type yoke 2 is flat as a whole, and is divided into an upper yoke 21 and a lower yoke 22, which are respectively sleeved above and below the horizontal section of the rectangular induction coil 5, and the distances between the upper yoke 21 and the lower yoke 22 and the upper and lower surfaces of the direct-rolled slab 4 can be adjusted by the action of the hydraulic cylinders connected to the upper yoke 21 and the lower yoke 22. The E-type yoke 2 is made of high-magnetic-conductivity silicon steel sheets, and a plurality of magnetic teeth are provided on one side close to the high-temperature direct-rolled slab 4, wherein the number of magnetic teeth is one more than the number of induction coils 5, including a first magnetic tooth 211, a second magnetic tooth 212, ..., and an n+1th magnetic tooth. A yoke refractory material insulation layer 3 (i.e., an upper yoke refractory material insulation layer 31 provided on the upper yoke 21 and a lower yoke refractory material insulation layer 32 provided on the lower yoke 22) is provided on one side surface of the E-type yoke 2 close to the direct-rolled slab 4 to prevent the high-temperature steel billet from directly baking the yoke and affecting the magnetic conductivity and service life of the silicon steel sheet.

[0047] Combination Figure 1 , Figure 3 As shown, in the motion actuator 1, the yoke adjustment mechanism includes a first hydraulic cylinder 11 connected to the upper yoke 21 and a second hydraulic cylinder 12 connected to the lower yoke 22. The distance between the upper yoke 21 and the upper surface of the direct-rolled slab 4 is adjusted by the first hydraulic cylinder 11, and the distance between the lower yoke 22 and the lower surface of the direct-rolled slab 4 is adjusted by the second hydraulic cylinder 12. The distance between the upper yoke 21 and the lower yoke 22 and the upper and lower surfaces of the direct-rolled slab 4 is adjusted online by the yoke adjustment mechanism, thereby reducing the induction heating magnetic field loss and improving the adaptability of the multi-magnetic circuit composite induction heating device.

[0048] Combination Figure 1 , Figure 3 As shown, in the motion actuator 1, the coil adjustment mechanism includes a third hydraulic cylinder 13 connected to the one or more groups of induction coils 5, and the height position of the one or more groups of induction coils 5 is adjusted by the third hydraulic cylinder 13, so that the center heights of the direct-rolled slab 4 and the induction coils 5 coincide with each other; in specific implementation, it is also possible to consider adjusting the induction coil while adjusting the yoke by the hydraulic cylinder, and the two cooperate with each other and work together to make the direct-rolled slab 4 basically in the center position surrounded by the E-shaped yoke 2 and the induction coil 5, which helps to further improve the uniformity of the induction heating temperature and enhance the ability of the induction heating device to adapt to different slab materials.

[0049] Combination Figure 4 , Figure 5As shown, the multi-magnetic circuit composite induction heating device of the present invention also includes a control center 300 connected to the motion actuator 1 and the variable frequency power supply 9; the control center 300 includes a slab detection system, a position controller and a power controller. The slab detection system is used to obtain information such as the steel type, thickness, plate shape, surface temperature, and running speed of the direct-rolled slab 4. The slab detection system includes a distance detection module 200 for measuring the thickness (plate shape) of the direct-rolled slab 4 and a temperature detection module 100 for detecting the surface temperature of the direct-rolled slab 4. The position controller is connected to the slab detection system and the motion actuator 1 respectively. The position controller adjusts the height position of the induction coil 5 and the E-type yoke 2 (upper yoke 21, lower yoke 22) of the composite inductor through the motion actuator 1 (first hydraulic cylinder 11, second hydraulic cylinder 12 and third hydraulic cylinder 13) according to the thickness of the direct-rolled slab, so as to improve the temperature uniformity and heating efficiency of the induction heating of the direct-rolled slab, and ensure that the slab can pass through the induction heating device smoothly. The power controller is connected to the slab detection system and the variable frequency power supply 9 respectively. The power controller adjusts the output power and current frequency of the variable frequency power supply 9 according to the data of the direct-rolled slab. Specifically, the power controller adjusts the output power of the variable frequency power supply 9 according to the initial temperature of the direct-rolled slab 4 measured by the temperature detection module 100, as well as the slab speed, slab thickness, and even comprehensive information such as steel type, and adjusts the current frequency of the variable frequency power supply 9 according to the thickness of the direct-rolled slab 4 measured by the distance detection module 200, so that the direct-rolled slab 4 can accurately reach the rolling temperature before the rolling mill 400 after induction heating.

[0050] The working principle of the multi-magnetic circuit composite induction heating device of the present invention is as follows: the induction coils 5 connected in series are applied with alternating current through the variable frequency power supply 9, and under the regulation of the E-type magnetic yoke 2, a strong alternating magnetic field is excited at the center of the induction coil 5, i.e., the position where the direct-rolled slab 4 passes through. The alternating magnetic field induces a large amount of eddy current within the skin effect depth range of the slab surface, and the greater the frequency of the alternating magnetic field change, the smaller the skin depth. When the eddy current flows in the skin layer on the surface of the steel billet with a certain resistance, it has an ohmic heating effect. The slab is electrically heated by eddy current by relying on ohmic heat, the temperature of the steel billet is quickly increased, and the heating function before the slab is rolled is realized.

[0051] The present invention arranges the above-mentioned multi-magnetic circuit composite induction heating device of the direct-rolled slab on the surface of the direct-rolled slab 4. When in use, the distance δ between the upper yoke and the lower yoke (including the refractory insulation layer) of the E-type yoke 2 and the surface of the direct-rolled slab 4 is 10-30 mm, which can be adjusted according to actual conditions. The induction coil 5 (including the refractory insulation layer) is generally located at a position where its center line is highly overlapped with the center line of the direct-rolled slab 4, which can be adjusted according to actual conditions. The current frequency f output by the variable frequency power supply 9 is 200-1000 Hz, and the output power P is 1-40 MW, which can also be adjusted according to actual conditions.

[0052] In the present invention, on the one hand, the advantages of conventional longitudinal magnetic heating, such as generally high efficiency and generally easy adjustment of transverse magnetic heating, are brought into play; on the other hand, the disadvantages of conventional longitudinal magnetic heating, such as generally inconvenient adjustment and generally low heating efficiency of transverse magnetic heating, are overcome, thereby forming a multi-magnetic circuit composite induction heating device for direct-rolled slabs. Among them, the main purpose of designing multiple groups of induction coils is to utilize the high electromagnetic conversion efficiency of the solenoid-type longitudinal magnetic coils, while reserving the necessary space for the up and down movement of the E-type yoke, and at the same time, it can also reduce the accumulated potential that often exists at both ends of the induction coil and the corresponding billet position, and prevent the "discharge" and "sparking" that often occur between the copper tubes of the coils and between the billets and the conveyor rollers due to excessive voltage, which affects the surface quality of the direct-rolled slabs and affects the operating safety of the induction coils and conveyor rollers; the main purpose of designing the E-type yoke with multiple magnetic poles is to minimize the longitudinal magnetic field existing around the induction coil through the magnetic conductivity of the yoke. The workpiece to be heated (straight-rolled slab) is guided, constrained and gathered toward the center of the coil, which minimizes the leakage and consumption of the induction heating electromagnetic field in the surrounding space, and shields the adverse effects of the induction heating electromagnetic field on the surrounding environment, such as the induction heating of the roller equipment, the electromagnetic interference of the electric control signal transmitted nearby, etc., thereby improving the electric-magnetic conversion efficiency of induction heating. Moreover, the position of the E-type yoke and the induction coil can be adjusted online by the hydraulic cylinder without replacing the induction coil, which improves the adjustability, adaptability and flexibility of the induction heating of the longitudinal magnetic coil, and improves the induction heating quality and induction heating efficiency of the slab.

[0053] The multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention is further introduced below with reference to specific examples.

[0054] Example 1

[0055] This embodiment uses the multi-magnetic circuit composite induction heating device of the direct-rolled slab of the present invention to induction heat the direct-rolled slab with a thickness of 230 mm. The specific process is as follows:

[0056] A 230 mm thick straight-rolled slab 4 to be heated is placed on the roller table of a conveying roller 6, an induction coil 5 is arranged around the cross section of the straight-rolled slab 4, and a variable frequency power supply 9 is electrically connected to the induction coil 5 through a cable 8; the E-type yoke 2 is flat as a whole, and is divided into an upper yoke 21 and a lower yoke 22, the upper yoke 21 is located at the upper part of the induction coil 5, and the distance between the upper yoke 21 and the upper yoke refractory material insulation layer 31 thereon and the upper surface of the straight-rolled slab 4 is adjusted to δ1=20 mm by the upper first hydraulic cylinder 11; the lower yoke 22 is located at the lower part of the induction coil 5, and the distance between the lower yoke 22 and the lower yoke refractory material insulation layer 32 thereon and the lower surface of the straight-rolled slab 4 is adjusted to δ2=δ1=20 mm by the lower second hydraulic cylinder 12, the upper yoke 21, the lower yoke 22, the induction coil 5, and the variable frequency power supply 9 together constitute a composite inductor, such as Figure 1 As shown. Inside the composite inductor, the first induction coil 51 is wound clockwise, the second induction coil 52 is wound clockwise, and the third induction coil 53 is wound clockwise. The beginning end 511 of the winding of the first induction coil 51 is connected to the positive pole of the variable frequency power supply 9 through the cable 8, the terminal 512 of the winding of the first induction coil 51 is connected to the terminal 522 of the winding of the second induction coil 52 through the cable 8, the beginning end 521 of the winding of the second induction coil 52 is connected to the beginning end 531 of the winding of the third induction coil 53 through the cable 8, and the terminal 532 of the winding of the third induction coil 53 is connected to the negative pole of the variable frequency power supply 9 through the cable 8. And so on, all the induction coils are connected. At a certain moment when the induction coil 5 is powered on, the first magnetic teeth 211, the second magnetic teeth 212, the third magnetic teeth 213, and the fourth magnetic teeth 214 of the upper magnetic yoke 21 and the lower magnetic yoke 22 close to the surface of the direct-rolled slab sequentially and alternately generate magnetic poles of N pole, S pole, N pole, and S pole, thereby forming three closed, oppositely directed, and adjacent induction heating magnetic field loops, such as Figure 2 As shown, since the thickness of the direct-rolled slab 4 is relatively large, this embodiment adopts an induction heating alternating current frequency of f=200 Hz with a deeper skin effect depth and an output power of 20 MW.

[0057] Example 2

[0058] This embodiment uses the multi-magnetic circuit composite induction heating device of the direct-rolled slab of the present invention to induction heat the direct-rolled slab with a thickness of 230 mm. The specific process is as follows:

[0059] A 230 mm thick straight-rolled slab 4 to be heated is placed on the roller table of a conveying roller 6, an induction coil 5 is arranged around the cross section of the straight-rolled slab 4, and a variable frequency power supply 9 is electrically connected to the induction coil 5 through a cable 8; the E-type yoke 2 is flat as a whole, and is divided into an upper yoke 21 and a lower yoke 22, the upper yoke 21 is located at the upper part of the induction coil 5, and the distance between the upper yoke 21 and the upper yoke refractory material insulation layer 31 thereon and the upper surface of the straight-rolled slab 4 is adjusted to δ1=20 mm by the upper first hydraulic cylinder 11; the lower yoke 22 is located at the lower part of the induction coil 5, and the distance between the lower yoke 22 and the lower yoke refractory material insulation layer 32 thereon and the lower surface of the straight-rolled slab 4 is adjusted to δ2=δ1=20 mm by the lower second hydraulic cylinder 12, the upper yoke 21, the lower yoke 22, the induction coil 5, and the variable frequency power supply 9 together constitute a composite inductor, such as Figure 1 As shown. Inside the composite inductor, the first induction coil 51 is wound clockwise, the second induction coil 52 is wound counterclockwise, and the third induction coil 53 is wound clockwise. The beginning end 511 of the winding of the first induction coil 51 is connected to the positive pole of the variable frequency power supply 9 through the cable 8, the terminal end 512 of the winding of the first induction coil 51 is connected to the beginning end 521 of the winding of the second induction coil 52 through the cable 8, the terminal end 522 of the winding of the second induction coil 52 is connected to the beginning end 531 of the winding of the third induction coil 53 through the cable 8, and the terminal end 532 of the winding of the third induction coil 53 is connected to the negative pole of the variable frequency power supply 9 through the cable 8. All the induction coils are connected in this way. At a certain moment when the induction coil 5 is powered on, the first magnetic teeth 211, the second magnetic teeth 212, the third magnetic teeth 213, and the fourth magnetic teeth 214 of the upper magnetic yoke 21 and the lower magnetic yoke 22 close to the surface of the direct-rolled slab sequentially and alternately generate magnetic poles of N pole, S pole, N pole, and S pole, thereby forming three closed, oppositely directed, and adjacent induction heating magnetic field loops, such as Figure 2 As shown, since the thickness of the direct-rolled slab 4 is relatively large, this embodiment adopts an induction heating alternating current frequency of f=200 Hz with a deeper skin effect depth and an output power of 20 MW.

[0060] Example 3

[0061] This embodiment adopts the multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention, and the specific process when the specifications of the direct-rolled slabs are switched is as follows:

[0062] When the thickness of the direct-rolled slab changes from d1 = 230 mm to d2 = 80 mm, combined with Figure 3As shown, the straight-rolled slab 4 to be heated is placed on the roller table of the conveying roller 6, the induction coil 5 is arranged around the cross section of the straight-rolled slab 4, the variable frequency power supply 9 is electrically connected to the induction coil 5 through the cable 8, the upper magnetic yoke 21 is located at the upper part of the induction coil 5, and the upper magnetic yoke 21 is lowered by 150mm through the action of the upper first hydraulic cylinder 11, and the distance δ1=20mm between the upper magnetic yoke 21 and the refractory material insulation layer 31 thereon and the upper surface of the straight-rolled slab 4 is adjusted; the lower magnetic yoke 22 is located at the lower part of the induction coil 5, and the distance between the lower magnetic yoke 22 and the refractory material insulation layer 32 thereon and the lower surface of the straight-rolled slab 4 remains unchanged, that is, the distance from the lower surface of the straight-rolled slab 4 is still 20mm, that is, δ2=20mm. The induction coil 5 and the coil refractory material insulation layer 7 thereon are lowered by 75mm through the third hydraulic cylinder 13, so that the center line of the straight-rolled slab 4 coincides with the center line of the induction coil 5, further improving the induction heating efficiency and induction heating quality. On the other hand, as the slab thickness becomes thinner, the current frequency is 1000 Hz with a smaller skin effect depth, and the output power is 10 MW, which results in a better induction heating effect.

[0063] Example 4

[0064] Due to the long-term contact cooling between the conveyor roller 6 and the lower surface of the direct-rolled slab 4, there are sometimes quality problems of uneven induction heating temperature such as "roller mark" and "yin-yang surface" (that is, the lower surface temperature is lower than the upper surface temperature). When this happens, the direct-rolled slab 4 to be heated is placed on the roller table of the conveyor roller 6, and the induction coil 5 is arranged around the cross-section of the direct-rolled slab 4. The frequency conversion power supply 9 is electrically connected to the induction coil 5 through the cable 8. The E-type yoke 2 is divided into an upper yoke 21 and a lower yoke 22. The upper yoke 21 is located on the upper part of the induction coil 5, and the upper yoke is adjusted by the upper first hydraulic cylinder 11 21 and the refractory insulation layer 31 thereon are positioned so that the distance δ1=25mm from the upper surface of the direct-rolled slab 4 is maintained. The lower magnetic yoke 22 is located at the lower part of the induction coil 5. The lower magnetic yoke 22 and the refractory insulation layer 32 thereon are adjusted by the lower second hydraulic cylinder 12 to make the distance δ2=15mm from the lower surface of the direct-rolled slab 4. The heating capacity of the inductor on the lower surface of the direct-rolled slab 4 is appropriately increased, which can better eliminate heating defects such as the "yin-yang surface", improve the uniformity of the induction heating temperature of the direct-rolled slab, and is conducive to the stability and smoothness of the subsequent rolling process, and also improve the performance and quality of the final plate and strip products.

[0065] Example 5

[0066] For the straight-rolled slab 4 (especially the thin slab), sometimes there are quality problems such as "warping" and "buckling" of the slab. For example, the head of the straight-rolled slab 4 is warped by 10mm. When this happens, the straight-rolled slab 4 to be heated is placed on the roller table of the conveying roller 6, and the induction coil 5 is arranged around the cross section of the straight-rolled slab 4. The variable frequency power supply 9 is electrically connected to the induction coil 5 through the cable 8. Through the control center 300, the first hydraulic cylinder 11 adjusts the position of the upper magnetic yoke 21 and the refractory insulation layer 31 thereon so that the distance δ1 from the upper surface of the straight-rolled slab 4 is equal to or less than 1. 30mm, the second hydraulic cylinder 12 adjusts the position of the lower magnetic yoke 22 and the refractory insulation layer 32 thereon so that the distance from the lower surface of the direct-rolled slab 4 is δ2=20mm, and the third hydraulic cylinder 13 adjusts the induction coil 5 and the refractory insulation layer 7 thereon to raise its position by 5mm, thereby increasing the opening of the inductor in real time to ensure the smooth passage of the direct-rolled slab 4 and prevent the moving direct-rolled slab 4 from damaging the inductor. In particular, this dynamic control can be implemented when the head of the slab passes through, and the inductor returns to its normal position after the head passes through, so as to improve the efficiency and effect of induction heating.

[0067] To sum up, the multi-magnetic circuit composite induction heating device for direct-rolled slabs of the present invention has the advantages of compact equipment, small footprint, flexible design, high efficiency, and easy use. It expands the range of direct-rolled slab induction heating, especially longitudinal magnetic induction heating, to adapt to different slab specifications, improves the quality of slab induction heating, especially the slab induction heating efficiency, reduces the induction heating cost during slab rolling, especially direct rolling, and is suitable for promotion and application in various continuous casting, continuous rolling or direct rolling production aspects, and has broad prospects.

[0068] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A multi-magnetic circuit composite induction heating device for direct rolling slab, characterized in that: It includes a composite sensor and a motion actuator; The composite inductor comprises an induction heating circuit and an E-shaped magnetic yoke; the induction heating circuit comprises one or more induction coils arranged side by side in the moving direction of the direct-rolled slab, a variable frequency power supply connected to the induction coils, and a cable connecting the induction coils and the variable frequency power supply; adjacent induction coils are connected in series; the E-shaped magnetic yoke comprises an upper magnetic yoke and a lower magnetic yoke respectively sleeved on the upper and lower sides of the horizontal section of the induction coil, and a plurality of magnetic teeth facing the direct-rolled slab are arranged on the side of the upper magnetic yoke and the lower magnetic yoke close to the direct-rolled slab; The motion actuator includes a yoke adjustment mechanism and a coil adjustment mechanism; the yoke adjustment mechanism is used to adjust the distance between the upper yoke and the lower yoke of the E-type yoke and the upper and lower surfaces of the direct-rolled slab; the coil adjustment mechanism is used to adjust the position of one or more groups of induction coils.

2. The multi-magnetic circuit composite induction heating device for direct-rolled slab according to claim 1, characterized in that: The induction coils are wound along the width direction of the direct-rolled slab; each group of induction coils is arranged between different magnetic teeth of the E-shaped magnetic yoke.

3. The multi-magnetic circuit composite induction heating device for direct-rolled slab according to claim 2, characterized in that: The induction coil is wound with a copper tube, the outer surface of the copper tube is covered with an electrical insulation coating, and the inside of the copper tube is cooled by circulating water.

4. The multi-magnetic circuit composite induction heating device for direct-rolled slabs according to claim 2, characterized in that: The inner surface of the induction coil is provided with a refractory insulation layer.

5. The multi-magnetic circuit composite induction heating device for direct-rolled slab according to claim 2, characterized in that: The winding directions of adjacent induction coils are opposite, and the electrode interfaces of adjacent induction coils are connected in sequence; or The winding directions of adjacent induction coils are the same, and the electrode interfaces of adjacent induction coils are connected in sequence.

6. The multi-magnetic circuit composite induction heating device for direct-rolled slab according to claim 1, characterized in that: The upper magnetic yoke and the lower magnetic yoke are both made of laminated silicon steel sheets, and a refractory material heat insulation layer is provided on the surface of the upper magnetic yoke and the lower magnetic yoke on a side close to the direct-rolled slab.

7. The multi-magnetic circuit composite induction heating device for direct-rolled slab according to claim 1, characterized in that: The number n of the induction coils is 1 to 8, and the number of the magnetic teeth of the E-shaped magnetic yoke is n+1.

8. The multi-magnetic circuit composite induction heating device for direct-rolled slab according to claim 1, characterized in that: The yoke adjustment mechanism includes a first hydraulic cylinder connected to the upper yoke and a second hydraulic cylinder connected to the lower yoke; The coil adjustment mechanism includes a third hydraulic cylinder connected to the one or more groups of induction coils.

9. The multi-magnetic circuit composite induction heating device for direct-rolled slabs according to claim 1, characterized in that: The cable is a flexible water-cooled copper cable.

10. The multi-magnetic circuit composite induction heating device for direct rolled slab according to claim 1, characterized in that: It also includes a control center connected to the motion actuator and the variable frequency power supply; the control center includes a slab detection system, a position controller and a power supply controller; The slab detection system is used to obtain the steel type information, running speed, thickness and surface temperature of the direct-rolled slab; The position controller is connected to the slab detection system and the motion actuator respectively, and the position controller adjusts the position of the induction coil and the E-type magnetic yoke of the composite inductor through the motion actuator according to the thickness of the direct-rolled slab; The power supply controller is connected to the slab detection system and the variable frequency power supply respectively, and the power supply controller adjusts the output power and current frequency of the variable frequency power supply according to the data detected by the slab detection system.

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